Polyolefins are the largest-volume family of commercially important, high tonnage thermoplastics and are produced by a worldwide industry with impressive capacity. Even more impressive is the wide range of polymer types and grades that have been obtained from simple starting materials, such as ethylene and propylene. Polyethylene has the world's largest market share among the polyolefins.
Modification of polyethylene is particularly attractive, because it may allow enhancement of existing polyethylene properties and may even confer new properties that may extend application potential. Polyethylene may have a reactive moiety, for example, a vinyl or vinylidene group, that may allow the polyethylene to be functionalized or to be used as macromonomers, allowing them to become further incorporated into another polymer chain. Vinyl groups tend to be more reactive than the more sterically crowded vinylidene groups. Vinyl terminated polyethylenes are therefore desirable. Additionally, polyethylenes that have about one vinyl end group per polymer molecule are even more desirable. If every polyethylene has a reactive moiety capable of being functionalized or otherwise modified, then there would be appreciable cost savings and efficiency in using such a polyethylene. Accordingly, there is a need for vinyl terminated polyethylene, particularly vinyl terminated polyethylene having about one vinyl group per polyethylene molecule.
U.S. Pat. No. 6,169,154 discloses a branched ethylenic macromonomer, derivable from ethylene singly or derivable from ethylene and another olefin, where (a) the molar ratio of a terminal methyl group/a vinyl group is in the range of from 1 to 100, the macromonomer having a branch other than the branch directly derived from the other olefin; (b) a ratio of vinyl groups to the total unsaturated groups in the macromonomer being 70 mol % or more; and (c) a weight average molecular weight of the macromonomer in terms of a polyethylene measured by a GPC being in the range of 100 to 20,000.
Huang et al. (Appl. Organometal. Chem. 2010, 24, pp. 727-733) disclose the synthesis of long-chain branched polyethylene including the generation of vinyl-terminated polyethylene macromonomers, using bridged cyclopentadienyl indenyl(fluorenyl) zirconocenes. The vinyl-terminated polyethylene macromonomers was reported to have a Mn(NMR) in the range of 3,300 to 10,300 g/mol and terminal vinyl percentages of 80.7% to 94.9%.
JP 2012/116871 discloses catalysts for the polymerization of olefins and the manufacture of olefin polymers with good particle shape. These catalysts comprise (a) solid aluminoxanes; (b) organometallic compounds of (b-1) AlR53 or (b-2) M3R52 (R5=H, halo, C1-20 hydrocarbyl or alkoxy, C6-20 aryloxy, M3=Mg, Zn); and (c) metallocenes of Group 4 metals. Olefin polymers were manufactured by the polymerization of ethylene and comonomers using the catalysts. The catalysts were reported to be useful for the manufacture of vinyl-terminated macromers. Thus, ethylene was polymerized in the presence of aluminoxane, dimethylsilylenebis(cyclopentadienyl)zirconium dichloride, and triisobutylaluminum to give polyethylene reported to have a Mn of 11,500 g/mol, molecular weight distribution of 2.4, and a selectivity of terminal vinyl groups of 0.59.
JP 2008/050278 discloses silylene(cyclopentadienyl)(indenyl)transition metal (Ti, Zr, and Hf) compounds, olefin polymerization catalysts containing them, and the manufacture of polyolefins. Polyolefins having vinyl end groups, useful as macromonomers, were manufactured with these catalysts. In particular, ethylene was polymerized with dimethylsilylene(cyclopentadienyl)(2,4,7-trimethylindenyl)zirconium dichloride, N,N-dimethyloctadecylamine HCl salt-treated hectorite, Et3Al, and (iso-Bu)3Al to give polyethylene reported to have vinyl end groups of 0.07/1000 C atoms.
JP 2007/246433 discloses metallocenes with long hydrocarbyl-containing bridging groups, olefin polymerization catalysts containing them, and manufacture of vinyl-terminated polyolefins. The metallocenes have the structure I, below:
[M1=Ti, Zr, Hf; X=H, halo, C1-20 hydrocarbyl, etc.; Cp1, Cp2=(substituted) cyclopentadienyl, (substituted) benzocyclopentadienyl, (substituted) dibenzocyclopentadienyl; substituent for Cp1 and Cp2=halo, C1-20 hydrocarbyl, C1-20 alkoxy, etc.; R1=C1-40 hydrocarbyl; R2=C21-40 hydrocarbyl; Q=C, Si, Ge, Sn]. Ethylene was polymerized with I (R1=Me, R2=docosyl, Q=Si, Cp1=Cp2=cyclopentadienyl, M1=Zr, X=Cl), N,N-dimethyloctadecylamine HCl salt-modified hectorite, and (iso-Pr)3Al to give polyethylene reported to have a number of vinyl end groups of 0.42/1000 C atoms.
JP 2007/169340 discloses ethylene polymerization in the presence of a catalyst containing (propane-1,3-diyl-biscyclopentadienyl)zirconium dichloride, (iso-Bu)3Al, and N,N-dimethyloctadecylamine hydrochloride-modified hectorite to give polyethylene reported to have a number of vinyl end groups of 0.05/1000 C.
EP 0 530 408 discloses vinyl-terminated olefin polymers, reported to have a Mn of 300 to 500,000, manufactured by polymerization of C2-3 alkenes in the presence of a reaction product of a polymerization catalyst consisting of a V chelate compound and a dialkylaluminum halide with CH2:CH(CmH2m)CH:CH2 (I, m=1-15), and then reacting with I and a proton donor. Polyethylene, reported to have a Mn of 300 to 300,000 and terminal groups COX [X=OH, OR1, halogen, SO3R2; R1=Cl−5 alkyl; R2=(un)substituted C1-20 hydrocarbyl] is obtained by polymerization of C2H4 in the presence of a dilithio compound. amine complex, followed by reaction with CO2 and a proton donor or sulfonyl halide. Thus, vinyl-terminated ethylene polymer was prepared by polymerization of C2H4 in the presence of Et2AlCl (where Et means ethyl) and tris(2-methyl-1,3-butanedionato)vanadium and 1,7-octadiene; for structure proof it was refluxed with a solution of diborane in THF and Bu2O and treated with aqueous NaOH containing H2O2. The OH-terminated polymer was then treated with Me3SiCl in pyridine to give trimethylsiloxy group-terminated polyethylene.
Britovsek et al. (J. Am. Chem. Soc. 1999, 121, pp. 8728-8740) discloses the synthesis, characterization, and ethylene polymerization behavior of a series of iron and cobalt halide complexes, LMXn (M=Fe, X=Cl, n=2, 3, X=Br, n=2; M=Co, X=Cl, n=2) bearing chelating 2,6-bis(imino)pyridyl ligands L [L=2,6-(ArNCR1)2C5H3N]. X-ray diffraction studies showed the geometry at the metal centers to be either distorted square pyramidal or distorted trigonal bipyramidal. Treatment of the complexes LMXn with methylaluminoxane (MAO) led to highly active ethylene polymerization catalysts converting ethylene to highly linear polyethylene (PE). LFeX2 precatalysts with ketimine ligands (R1=Me) are approximately an order of magnitude more active than precatalysts with aldimine ligands (R1=H). Catalyst productivities in the range 3,750 to 20,600 g/mmol·h·bar were observed for Fe-based ketimine catalysts, while Co ketimine systems displayed activities of 450 to 1740 g/mmol·h·bar. Molecular weights (Mw) of the polymers produced were in the range 14,000 to 611,000. Changing reaction conditions also affected productivity and molecular weight; in some systems, a bimodal molecular weight distribution was observed.
However, few processes have been shown to produce a high percentage of vinyl chain ends, in high yields, with a wide range of molecular weight, and with high catalyst activity for ethylene-based polymerizations. Accordingly, there is need for new processes using catalysts that produce polyethylene polymers having a high percentage of vinyl chain ends, in high yields, with a wide range of molecular weight, with a narrow molecular weight distribution, and with high catalyst activity. Further, there is a need for ethylene-based reactive materials having vinyl terminations which can be functionalized and used in other applications.